Crucible tongs for side-access furnace

I have a David Gingery inspired side-access furnace. The tongs he recommends in his furnace book are copied below:



Besides adding another twist to the reigns to make them more comfortable to grip, I was thinking of adding a vertical "hook" to the top of grabbing end. Since the circular part fits below the middle "bulge" of the crucible, the "hook" will prevent the crucible from slipping out while pouring. I've seen this on many other designs, but what do y'all think?

 

For an A8, Gingery recommends 1/4" x 3/4" mild steel for the curvy part. I picked up some 1" wide material instead, along with a short length of 5" diameter schedule-40 pipe.



Based on my "bent up wire" calculations, that pipe diameter (roughly 5-1/2") plus another 1/2" should fit nicely around the midsection of my crucible. So I'll simply to forge the 1/4" bar around the pipe twice.





Then I tack-welded the small ring on so it won't move around while I form the larger ring.



I don't have a proper forge, and don't feel like trying to use my furnace for the task, so I'm just using my (very old) Victor 100 torch with Oxy-propane gas.







I think this is a good spot, maybe could make it a little tighter? Remember I plan to split this ring in half. Attaching each half to tong handles (reigns I think they're called).



Just in case it makes sense to have TWO grabby parts, I busted off the tacks on the smaller ring.



This will make me feel safer, but the cost is quite a bit of extra weight right on the end where I'll suffer lifting it the most



Anyone have a suggestion/opinion on two rings or one?

 

I built Dave's tongs and added an ear below each jaw. Sometimes I used a #6 crucible so although it sits lower I don't need another set of tongs.
You are on the right track and they are easily adjusted.

 

Oh great! I'm happy you're sharing your experience, thanks!

Oh! That's really great and (more importantly) simple idea, I like it! Thanks for the suggestion!

I think I'll follow this, and just save the little ring for something else.

 

Used a die-grinder, angle-grinder, and belt sander to smooth the sharp factory edge that's in contact with the crucible.



After a bunch more hammering and fussing, I got the fit pretty good. Perhaps five points of contact on each half (a bit hard to see in photo). Should I worry about this more?



Welded on four 1/2" x 1/8" support ears as @ESC suggested, to on each side. These were supper fiddley to fixture, lots of balancing and carefuling was required. I got three solid welds on each ear, should be plenty strong enough.



I only managed to screw up one - the last one of course. But nothing a grinder and a do-over couldn't fix.



I think the next step is to split the ring in half. Then try and find a good pivot point and rivet together the handle stock. Followed by adding a half-twist. Gingery recommends bending in a 1-2° angle at the crucible-end, to help account for "droop". I think instead I'll just grind a slight angle at the point where the handles get welded to the ring. Thoughts?

I'm also thinking I may want to add some small gussets (triangle-pieces) to better support the handle/ring connection. Worth while?

 

It took me two tries, but I was able to get a pair of gussets made which match the OD of the ring basically perfectly. These will be welded on to support the handles as mocked up below in the pic.



My screw up: I tried to make them one by one out of small pieces of material. I would have been successful given lots and lots of time, simply because they heated up working them too much to hold onto. So it was much better to make them one at a time, leaving them attached to a long stick of material to hold onto.

 

Since there is a pair of long handles, I'm using slightly thinner, 1" x 5/16" x 4' material (instead of the 1" x 1/4" of the grippers). First step was identifying where the pivot will go (roughly 6" from the end), then clamping that 1" shorter (for rivet clearance) and giving a half twist.



I drilled and chamfered a 3/8" hole at my marked location, through both handles. Then temporarily bolted them together (the rivet will come at the end). Clamped the handles 1" further away from the bolt hole, and added another half-twist (in the same direction).



Loosened the bolt slightly, and checked the action operates smoothly. The handles are 4' long, so I couldn't fit them all in frame



In my decades on this earth, I've only ever needed one 3/8" rivet, and don't want to store a big collection of commercial pieces. So next, I'm building an upsetting jig (for making rivets and other round-bar bending/forming operations). Once my rivet is ready, I'll be un-bolting the handles, welding the grippers, and gussets onto them, then doing in final test-fit/adjustment on my crucible before riveting.

 

I made a 3/8" test-rivet, set into a counter-sunk hole, using a home-made upsetting jig to hang onto the other end of bar-stock. The secret turned out to be going really slowly. Not trying to form the rivet with a few really hard blows. Instead using controlled and "medium" hard hits while keeping the rivet almost yellow-hot.



Set the rivet in another piece of handle-material scrap, to both learn, and prove to myself I could handle a rivet of this size. It wasn't nearly as easy as I made it out in my mind Sent the whole thing flying across the room a few times, red-hot of course A proper anvil might have helped, and using the blacksmith's third-hand



I need a better way to hold the handle material in place while I heat & beat on the rivet. Wood-working clamps just aren't up for the job Anybody have suggestions?

 

Spent about four hours grinding all the mill-scale off of the handles. Then I spent about an hour with a die-grinder, removing all the sharp corners/edges from the gripper head halves. Finally, using the inner forming steel ring from the beginning to hold the gripper halves together, I clamped the whole assembly together in preparation for tack-welding.



Note: The rivet I made is simply stuck into the pivot hole for fixturing. Smashing a head onto it will be the final step after everything is all welded up.

After tacking, I'm thinking I'll do a final test-fit on the crucible before welding the head-halves onto the gussets and handles. As a final touch before painting the handles, I think I'll add some kind of top-catch to stop the crucible from accidentally falling out of the top during a pour.

I've seen some fancy catches before, but I'm more inclined toward simple rather than fancy. Likely I will just weld on be a piece of bent 1/2" x 1/8" steel, the same I made the bottom "ears" out of. Though I'm open to clever suggestions if anyone has any

 

Does the crucible ring grip about 1/3rd the way up the crucible?, that helps balance when pouring, when the crucible is half empty. You can also weld some steel tabs above the ring to stabilize the crucible during pouring.
You'd probably want to hold the tongs with a gloved hand just after the pivot to support the weight of the crucible/metal while pouring, so some kind of radiant heat shield made from sheet metal would be very useful. That way the gloved hand is in the shadow of the infra-red radiant heat from the crucible. Even with molten aluminium there can be enough heat to cause your leather gloves to smoke (also use light colored gloves for that reason). Once you

 

Approximately, maybe slightly (1/2" or so) higher. Here's an upside-down pic of the fit, before I split the ring in half:



Once I've got everything tacked up I'm planning to do another test-fit on the crucible. It's not too late for minor adjustments at this stage.

Ya, that's what I was thinking of, a piece of 1/2" x 1/8" with a 90° bend at the top maybe 1/2" beyond the top edge of the crucible.

In this design the pivot is about 6" away from the gripping ring, so probably don't want to get my hand that close Gingery's drawing has the pivot even closer.



I have some thin, polished sheet aluminum lying around, I could make a heat-shield from that. What would you suggest, maybe 18" away from the gripping ring? The handles are 4' long for reference.

Yeah, it's good advise, I expect it's quite intense. My TIG gloves are bright white, and when they get dirty I replace them b/c they start to pick up too much radiant heat from the arc. I'm thinking I'll try and find some beefy stick-welding gloves for foundry work, esp. pouring. Along with a laundry-list of other safety gear (like a mesh face-shield, aluminized boot covers, maybe an apron, etc., etc.).

 

That current height you have should be fine, when it's full the balance should be neutral and when the level of the metal is level with your handle there should be some crucible mass above the handle to counter balance the metal left in the crucible below the handle. The worst case scenario would be the handle in line with the crucible rim which would mean you are fighting the weight of the metal in the crucible when trying to pour. I'm using the old school approach of a separate crucible lifter and a separate pouring shank so the heat shield design would not be the same. It doesn't have to be heat reflective at all, so long as the material is heat resistant and casts a shadow over your gloved hand. The shield even has a separate piece to cover the slot cut out of it as enough light shines through the gap to be uncomfortable.

So long as your gloves aren't a dark colour they should be fine, but avoid black, dark blue etc. as much as possible. I should see if I could buy some of that tennis shoe white compound to whiten the gloves on top. Even a plastic face mask will stop metal from hitting your face long enough to discard the mask. There's another young guy on the forum here who forgot to preheat his steel ingot moulds which caused a steam explosion and coated his clear plastic mask with brass droplets and saved him. The foil coated stuff is fragile, even leather welders spats over leather boots with a leather apron should do the job.

 

Ahh okay, I suspected something like that might be the case. Thanks for spelling it out more fully, I think I understand now. I can certainly try it out with 10-lb of scrap overloaded into the crucible. Worst-case I can weld on a "T" like you have on your handle. Thanks!

I think mine's going to need to be different since the handles split in two. I'll need a shield half attached to each side, with some overlap in the middle to cover up any gaps as you suggest. Thanks for the feedback.

Yeah, yet another reason why I really want to find one of those mesh masks and other foundry-specific garb. I too have f****d up an aluminized guards, while I was learning to torch-weld Though it did actually protect me (before, and while sacrificing itself) I think it's important to remember that all safety gear are wear items, even if they're expensive

Okay, you've given me some inspiration, and a good story or three I'll spend some time thinking/designing up a heat-shadow contraption, similar in size to yours and figuring out a way to attach it. Thanks!

 

On a related note I bought a Ryobi helmet and face mask for tree trimming from the hardware store and noted the face shield is black painted woven metal mesh so it may do the job.

 

My current PPE setup:
existing yellow hard hat
grim reaper w/'have a nice day' type smiley face sticker from coffee house on hard hat
Amaz*n welding jacket, apron with long legs, spats (edit: this line all leather, not cloth)
farm store welding gloves
leather boots
shade 2 or 5 glasses when I can find them to bring along.
Stuff from Cyberweld, attaches to existing hard hat:
Jackson 40 Mesh Wire Face Shield 29081
Jackson 137 Capshield 14948

pretty much the uniform of the cast iron art pour groups in the Midwest USA. A common add is a leather neck flap to the back of the 'lids', along with other decorations on helmets and jackets.

 

Thanks for the PPE rundown guys, I'll have to make a note to refer back when I get to that stage (soon hopefully).

Alas, the tongs are in trouble Here's the progress so far: Spent about four hours cleaning mill-scale (should have used acid, I even have some ) and setting up some complex fixturing in order to weld on the handles:





After all that, I did a test fit on the crucible. First impressions:

1. I welded the handles on upside-down , the anti-sag offset should be facing upward relative to the crucible (down, into my welding table in the pic) I think I can fix this with some heating and beating. Or I can grind off the tacks and re-position, but that might be more difficult
2. There's a tight-spot (pressure-point) on the crucible where the handles connect, and at the opposite side on gripper ends (at the gap). I think this is easily fixed with some heating and (gentle) beating
3. With a pivot 6" from the grippers, the end of the handles (4' away) has to open really really wide. This isn't operator friendly. I'm thinking of cutting-down one side of the handles, since it really only needs to be long enough for my "front" hand to operate. Another option is to simply enlarge the gap at the front of the grippers (like in the Gingery drawing). Anyone got a better idea?
4. In the sideways/pouring position, there's way too much flex in the handles. I think I can fix this by converting the front-most section (or the whole handle?) into a "T" profile. In other words, welding on a piece of (maybe 1/2" x 1/8") down the handle center, oriented 90° down the long-axis. Is there a simpler way anyone can think of?

 

Depending on how your furnace door is sized, you can probably fit the tongs over the top of the crucible without opening them fully or cutting bits off. Maybe some identical strip material to your tongs could be welded from the sides of the ring halves back to the pivot forming a braced triangle. The rest of the handles could be steel tube to get some stiffness, like 1/2" bore galvanized water pipe or some 3/4" square hollow steel, that would save an awful lot of welding gussets.

 

Excellent, thanks for the feedback and pics. I like your design, Gingery would probably have liked it too Looks like there's quite a bit of room for me to trim back on the grippers.

 

The opening is about 17", so this is plausible. Though based on Kelly's input, it looks like I can afford to trim the grippers down by maybe 1" on each side. That will make the handles a lot easier to operate. I can also put some offset-bends in them so they don't fold together completely when the gripper is in the closed position. That aught to help as well.

I think the head connection to the handle is plenty stiff with the gussets I already tacked on. But yours is a good suggestion, triangles always make everything more better

I don't mind the welding. I am concerned about the weight. I'll do some rummaging through my scrap pile, I think I have some 1/2" square-tube that might work. IIRC, it's got fairly think walls (for 1/2" tube), perhaps 1/16" or 3/32", can't remember off-hand.

Thanks for the feedback and suggestions, I appreciate all the ideas and considerations.